The AAD recommends the following steps for patch testing a new skin care product:
- Apply the product to a small patch of skin where a person is unlikely to accidentally wash or rub it away. Good areas may include the inside of the arm or bend of the elbow.
- Apply the product to a quarter-sized patch of skin. A person should apply the product as thickly as they would when using it regularly.
- Leave the product on the patch of skin for as long as it would normally be on the skin. If a person is testing a product that they would usually wash off, such as a cleanser, they should keep the patch on for 5 minutes or as long as the instructions advise.
- Repeat the patch test twice a day for between 7–10 days. A reaction may not happen immediately, so it is important to continue applying the product for this length of time.
- If a person’s skin reacts to the product, they should wash it off as soon as possible and stop using it. A person can use a cool compress or petroleum jelly to relieve the skin if needed.
Skin care products may contain many different ingredients. Some of these ingredients can irritate a person’s skin or even cause an allergic reaction. By performing a patch test on a small area of skin, a person can see how their skin tolerates a product before committing to using the product over a larger area.